Telephone system.



x 0. M. LEIGH. TELEPHONE SYSTEM. APPLICATION FILED JUNE 19, 190B.

Patented 001;. 26, 1909.

UNITE errrs AT i hi3.

OSCAR M. LEIGH, OF GENOA, ILLINOIS, AESIGNOR TO CRACRAFT-LEICH ELECTRIC (30., OF GENOA, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHQNE SYSTEM.

of Illinois, haveinvented a certain new and useful Improvementin Telephone Systems, of which the following is a full, clear, conelse, and eXact"description, relerence being had to the accompanying drawings, forming a part of this specification.

My invention relates to telephone Systems, and has for its object the provision of an improved system which has its application more particularly in railway service, where it can be used to transmit messages from oneend of the line-to the other, and where over illGiSflIllQ circuit used fin this long distance trausi-nission a plurality of local con-.

versationsbetween stations can be maintained. p

Details and advantages of this system will bemore apparent from the following description, taken in connection with the accompanying drawing, illustrative of one'embodiment thereof. In this drawing the circuit arrangements and also portions of. the

- apparatus are shown diagrammatically.

I employ two line conductors, 1 and 2, which unite various stations, A, B, C. At each station I provide a repeating coil, consisting of the primary windings, 3, 3, and the secondary windings, 4, 4, which repeating coil renders the conductors 1 and 2 continuous through these stations. These repeating coils, consisting of the coil 3, 3and 4, 4, I have designated by the numeral 5. In association with each repeating coil 5 there is a repeating coil 6, having windings 7 7 in inductive relation to a winding 8; The winding 8 is in series with a telephone 9.

It will. be apparent from the illustration given so far that the telephones 9, 9 can in tercommunicate with each other using the conductors l and 2, which provide for this communication a metallic circuit. The conversation, for ins'tance.from the left-hand telephone 9 is transmitted from the wind-' ing 8 to'the windings 7, 7 and is transmitted to the coils 4, 4, whichare in series with the coils 7, 7 and (1011s 4, 4, in connection with coils 3, 3,.project the voice current in bothdirections over the line wires '1 and 2. Longdistance' communication therefore may be had between the various telephones 9, 9, '9, the number being increased to ,suit the num- Specification of Letters Eatent.

Application filed June 19, 1908.

Serial 0, 439,312.

ber of blocks or stations which comprise a division. It is necessary in railway service Patented oer. as, race. v

not only to provide this long-distance communication, so that the train despatcher can talk to any station along the line, but it is 7 also necessary to provide service so thateach station can talk with its adjoining station on either side. To obtain this result, 1 provide a jack 10, one contact of which is connected between the coils 3, 3, and theother contact of which is connected to ground. In

connection with this jack, I use a plug 11,

having connected'to it a receiver 12, an induction C011 13, a battery 14, and a trans nutter l5, likewise a generator, 16. Thus,

'when the plug 11 is inserted in the jack 10,

voice currents can be propelled over the line wires 1 and 2, which now operate in parallel for this talking service and the ground.

The coils'3, 3 do not offer any special impedance, because of the fact that one terminal of the jack is connected between the coils 3, 3, so that currents through these coils flow in opposite directions, and they therefore act differentially, and in. the ideal case there is no magnetism in the core due to the convcrsat-ion received from the telephone connected with the plug 11. It is likewise apparent that with this construction no talking currents are transmitted from the coils 3, 3 to the coils 4, 4, so that if we take the middle telephone at station B, for instance, and it is connected in the jack 10, it can hold communication with jack 17 of station A only, or if the plug 11 is inserted injack 17 of station B, it can hold communication only with jack 10 of station C. If it is desired to hold a conversation from jack 10 of station B, for instance, with jack 1? of station A, the plug 11 is inserted in jack 10 of station B, and the generator lti operated to ring. the bell'18. It will be apparent from this, therefore, that a conversation over the two line wires and ground can he maintained between stations A and B, between B and C, between station C and the stationto the right (not here shown), and between station A and its if saryto use a very high frequency calling current in the telephones 9, 9, 9, which high frequency calling device is the subject of another application of mine.

I It will be seen from the illustration that jack 17, instead of being connected between the coils 4;, 4, as would be the case if these two coils were joined together, is connected 1 midway between coils 7, 7, which accomplishes the same object.

This system is adapted for train despatching purposes, in which case telephones 9, 9, 9 are used, and local conversations, together with the ordinary inter-station. block signals can.be had between the jacks 10' and 17 of the various stations; a

I have herein shown and particularly described one embodiment of my invention, and

What 1 claim as new and desire to secure by Leters Patent is: v

1. A telephone system, com rising a metallic circuit, repelatlag coils or maintaining the continuity of said circuit, a plurality of telephone instruments associated with saidcircuit, for the purpose of metallic intercommunication, a plural'ty of groups of telephones likewise associat d with said circuit, and arranged along said circuit in tan dem formation, so that intercommunieation can be held between the tele bones of each group, and repeating coils or preventing telephonic intercommunication between the first aforesaid telephones and the grouped telephones.

2. A telephone system, com rising a metallic circuit, repeating coils or maintain-;

ing the continuity of said circuit, a plurality of telephone instruments associated with said circuit, for the purpose of .metallic intercommunication, hlgh frequency calling and signaling devices provided for said telephones, a plurality of groups of telephones likewise associated with said circuit, and arranged along said circuit in tandem formation, so that intercommunication can be held between the telephones of each group, and repeating coils for preventing telephonic intercommunication between the first aforesaid telephones and the grouped telephones. 3. A telephone system, comprising a me tallic circuit, repeating coils for maintaining the continuity of said' circuit, each winding of said repeating coil being divided into two component parts, a second repeatin coil associated with each of the aforesaid repeating coils, one of the windings of each' of the la -aforesaid repeating coils being connected in series with the winding of its associated repeating coil first aforesaid, a telephone instrument associated with the second winding of each of the last aforesaid repeating coils, telephone instruments adapted for connection midway between the Windings of the first aforesaid repeating coil and the ground, and high frequency signaling arrangements provided for the first aforesaid telephones.

at. A railway telephone system, compriscult in combination with a central station and a plurality of substations, of a teleing a metallic line circuit and a return cir-,-

phone set at each of said stations arranged for metallic intercommunication over said has circuit, electro-magnetic meansfor establishing a plurality of adjoining, non-interfering telephone circuits in tandem ary rangement over said line circuit and return circuit, said last mentioned circuits not interfering withthe metallic circuit telephones aforesaid, and said last mentioned circuits being continuous between and ending at the various substations, a second telephone set at each substation, and switching instrumentalities for connecting same to eitherone of the adjoining last mentioned circuits terminatingat its associated substat on.

5. A railway telephone system, comprisf -ing a metallic line circuit and a return cir cuit in combination with a central station and a plurality of substations, of a telephone set at each of said stations arranged for" metallic intercommunication over said line.

circuit, electro-magnetic means for estab-" I llshing a plurahty of" ad o1nmg, non-lnterfering telephone circuits in tandem arrange ment over said line circuit and return .011-

cuit, said last mentioned circuits not interfering with the metallic circuit telephones aforesaid, and said last mentioned circuits being continuous between and endlng at" the various substations, a second telephone set at each substation, switching instrumentali-L ties for connecting same to either one of the; adjoining last mentioned circuits termlnating at its associated substation, and high frequency vibratory signal recelvlng devices associated'with each of the first aforesaid metallic telephones.

In witness whereof, I hereunto subscribe my name this sixth day .of June A. 1)., 1908. OSCAR M. LEIGH.

Witnesses:

O. M. NERMIGI-I,

E. B. CAMPBELL. 

